The present invention relates to a lubricator, and more particularly to a lubricator including a body defining therein a passage for a fluid under pressure and a restriction member displaceably disposed directly in the passage for suitably regulating the amount of oil to be atomized in the flow of the fluid under pressure, thus eliminating an oil needle valve to achieve a large reduction in the size of the lubricator.
When driving a cylinder device serving as a pneumatic device, a certain amount of lubricating oil is mixed with a working fluid to reduce friction and wear caused on the sliding surfaces of a piston and an inner cylinder wall.
Generally, lubricators are widely used to mix the lubricating oil with the working fluid. When air under pressure is supplied to the passage in the body of the lubricator, a differential pressure is produced upon passage of the air under pressure through a venturi defined in the passage. The lubricating oil stored in a lubricator case is caused by the differential pressure to be atomized and mixed with the air flow under pressure, and is supplied together with the air into the cylinder.
One general conventional lubricator is illustrated in FIG. 1 of the accompanying drawings.
The lubricator comprises a body 2 having a fluid inlet port 4 and a fluid outlet port 6 which are held in communication with each other through a passage 8. The passage 8 has a venturi (not shown) disposed substantially centrally in the body 2 and having an opening of a reduced cross-sectional area. A projection 10 of a bent cross section is disposed on the upper end of the body 2 and includes a needle valve 12 and a dropping window 14. An oil supply port 16 is also disposed on the top of the body 2. An oil conduit tube 18 and an oil reservoir case 20 are fixed to the lower end of the body 2, with the oil conduit tube 18 having an end immersed in oil stored in the oil reservoir case 20.
When air under pressure is supplied from an air supply to the fluid inlet port 4, the air flows through the passage 8 and is supplied from the fluid outlet port 6 to a desired location. As a portion of the air in the passage 8 is introduced via a non-illustrated passageway into the case 20, the air pressure in the case 20 is increased. When the air in the passage 8 passes the venturi (not shown), a pressure drop is developed as the air flows through the different cross-sectional area of the passage 8. Therefore, the pressure in the dropping window 14 which communicates with the passage 8 through the passageway is equalized to the reduced pressure in the passage 8. The oil in the case 20 is now forced through the oil conduit tube 18 and another non-illustrated passageway into the needle valve 12 under the pressure difference between the air pressure acting on the oil in the case 20 and the air pressure in the dropping window 14. The oil then drops from the needle valve 12 into the dropping window 14 so as to be atomized via the passageway into the passage 8 in which the atomized oil is mixed with the air flowing under pressure therethrough. The oil mixed with the air under pressure is then delivered to a port of a cylinder (not shown). The amount of oil dropping into the dropping window 14 can be varied by adjusting the needle valve 12.
As can easily be understood from FIG. 1, the conventional lubricator is quite large in size since the oil supply port is disposed on the body and the upwardly projecting needle valve is mounted on the body. In recent years, control devices operable under fluid pressure are widely used at production sites to meet demands for automatization and higher efficiency of operation. In addition, it is also desired to reduce the size of these control devices as much as possible for the purpose of increasing an available space in factories. The conventional lubricator however fails to fully meet the above demands.